Valve gear for steam turbines and the like



2 smsETs-sx-IEET 1 F. H. VAN NEST ET AL VALVE GEAR FOR STEAM TURBINES AND THE LIKE Filed March 25, 1949 Oct. 14, 1952 F. H. VAN NEsT ET A1. 2,613,542

VALVE GEAR FOR STEAM TURBINES AND THE LIKE Filed March 23, 1949 2 SHEETS-SHEET 2 Pig. Z.

Inventor: Francis r1.\/enNest, Lam/Pence B Wales,

13g-MM The r- Attorney Patented Oct. 14, 1952 UNITED vsTltTizs PATENT oFFIci:

Witvis eEARroR STEAM TURBINES .AND .THE

"Francis vH. :Van iNest and Lawrence B. Wales, Marblehead,fMess-, assiencxs t General Elec-l ftrie Company, a ,corporation of New kYork' Appliance-Marchas; 1949,fs eria1No..sac4/e 3 Claims. 1 This invention relateslto valve-gear and.V more particularly to an improved valve-gear forroperating valves vinfsteam 'turbines Y or the like.

In steam turbines and'the'likethe admissionof steam to the lturbine is.contro1led in la' conventional manner byfone or mores/alves `operated by one or more valve operating -.rods-fpositioned in the turbine. The valve Joperating ,rods in turn are actuated byfan oilhydraulic motor Vconnected to .the-valve operating yrods through a Valve gearl comprising a mechanical linkage.

In such 'an arrangement.- it-is desirablefthatthe loss of motion betweensthe hydraulic *motor and the valve operating-rodsfbe lminimizedvin order to provide the best-speed. control of-the turbine. i

In considering theffpossible-loss offmotion between the hydraulic Amotor and the Avalve .operatinglrods it will be .apparent Y'that 1such :lossfof ,motion through a mechanical linkage-Yislproportionalxto the force applied to thelinkage and the `flexibility 1 of the linkage. In thecase of. afstearn-turbine the force which `must be' applied to y open vthe valves under steam pressure islconsiderableibecause such force must act inropposition Atofaconsiderable pressure of steamtendingito bias the valves closed. Therefore: the-f force-l transmitted through the linkage operating thefvalves `is consderable and 1 a corresponding -rigidity in l the linkage must be providedf11o-compensate for-the heavy pressure 'appliedfthercta One conventional method# of 'providingdtha required rigidity in theflnkageis tOshprten-the overall length of thelinkage f'Ihis-met;l-1od,-al though successful insofar fas, operation of the turbine is concerned, has a disadvantage of nre hazard in that-with a short linkage,A thehydraulic motor, using oil asv an -operati-ngfiuid-mustbe mounted close tothe vsteam" turbinewhose1op erating steam temperatureis .above-'the fiiash point of the oil in 'the-hydraulic-motor and,r therefore, any oil leaking from the hydraulicmotor on the turbine mayY 4cause-a` fire".

It is an object of -ourfinvention tot provide i a valve gear which will A not produce excessive lost motion between the hydraulic motor-fand the .memberfi `a second bellcrankactuatedrnember 11n general, our :invention consists Aof a :valve .gear comprising, a main frame ,plate arranged for mountingon a steam turbine or the like ina projecting manner, a plurality of rpedestalsse- `cured .to -the main frame plate, a plurality of members pivotally secured one to each of ,the

pedestals and interconnected by parallel tension members therein7 forming a mechanicallinkage,

means connecting one portion of the linkage to aahydraulic motor `mounted ontheprojecting end of themain'frame, 4and means for vconnecting ,another portion of; the linkage to-.a valve operatng rod positioned in theturbine.

`Fora completeunderst'anding of^ our invention, reference -should be had to the following specicationand the accompanying drawing in which Fig. l is aside view, partly in c'rossysection of my invention as applied toma steam turbine,-Fig.` 2 is( a plan view oiFig. 1,` and Fig. 3 is an enlarged view of a portion of Fig. .1 partly in cross-section.

Referring `to the drawing, in Fig. 1 we have vshownpfor the purpose of illustrating our-'drivention, a steam chest |of vatype found on conventional stearn turbines, a `plurality .f oi valve seats 1 2 infthefsteamchest l and a plurality of-A'inlet valves 3. Inletvalves 3, are slidably. cor1r1 e :tedl by valve sterns 4 ,-to, a lcross-rmeinber 5 v which isfpperated by valvegoperatine rods; and steered thereto Yas shovvn in Fig.` 1. The valve'istemsnd `are .oiunequal length and areprovidedwithjstops V whereby whengcrossmember 5 is raised by the valve ,operating rods-6 and 'ithe variousvinlet vvalves ,Sgare opened in succession to V allow steam to flow from steam chestl to thevariousinlet :supply lines;,9. thereby regulating the-ammini 0f .Steam deliv er e d to `the turbine nozzles ed and zeonsecuently..regulating, the Speed 0f theeieam turbine u (notV s hwrl.)

f To factuate `the valve operatingrods. Band Al and thereby to operate theinletvalves 3 `irraccordance WithV my invention, we provide a `valve gear-HJ comprising amain frame plate; l l, atruss pedestal I2,- a first valve pedestal l 3a2 second Valve -pedestal 14,; a yrst'bellferank; actuating `I 6aythi1d ,bellcrankyactuatedl member `Il '1,V a first Apair vof parallel-tension -rods i8 pivotally interconznecting thefactuating member 1 l5 andthe actuated memberd.. and a second p airaof parallel .tension vrods t9- pivotally interconnecting the actuatedmembers IB and l1 respectively.

The main rarneplate ll .isimadezroi steelor other l. suitable j'. material and has an elongated rectangular. shape- :suitable` for .rigid mOllrlting on steam chest I in a projecting manner as shown in Fig. 1. On the projecting end 2|] of the main frame plate I I a conventional spring biased single acting hydraulic motor 2| is` secured by studs 22 and 23 or other suitable means. Motor 2| has a piston 24 which is arranged to move in an upward direction under pressure of oil and a spring 25 biasing the piston 24 in the opposite direction.

Truss pedestal I2 is made of steel or other suitable material and comprises two parallel truss plates 26 mounted longitudinally on main frame plate I I adjacent projecting end 26 thereof and connected by a cross plate 21 as shown in Figs'. 1 and 2. Cross plate 21, parallel truss plates 26, and main frame plate II are rigidly secured one to the other by means of welds 28 or other suitable means, thereby forming a rigid cantilever beam structure.

Actuating member I comprises two parallel arms 29 interconnected by a bridge frame portion 3|) having a bifurcated end 3| as shown in Fig. 2. The bridge frame portion 3|) is secured to the parallel arms 29 by welds 32 or other suitable means to form an integral rigid structure. The actuating member I5 is pivotally secured to truss pedestal I2 by means of a bearing shaft 33 passing through aligned apertures 34 and 35 located respectively in the parallel truss plates 26 and in the parallel arms 29 of actuating member I5. The bifurcated end 3| of actuating member I 5 is pivotally connected to one end of a piston rod 36 by means of a bearing shaft 31 passing through aligned apertures 38 and 39 located respectively in the bifurcated end 3| of actuating member I5 and the one end of piston rod 36. The other end of piston rod 36 is connected in any suitable manner to piston 24 of hydraulic motor 2|.

The iirst valve pedestal I3 is made of steel or other suitable material and comprises two parallel plates 40 connected by a cross-plate 4I, as shown in Fig. 2, forming a rigid structure and is secured to main frame plate I I by welds 42 or other suitable means as shown in Fig. 1.

The rst actuated member I6 is similar to actuating member I5 in that it comprises two parallel arms 43, and a bridge frame portion 44 connecting the parallel arms 43 and forming an integral rigid structure with a bifurcated end 45 on the bridge frame portion 44. However, the rst actuated member I6 is mounted on the rst valve pedestal I3 to allow a limited rotation about a. Vertical axis as well as a pivotal motion about a horizontal axis. The reason for this will be explained in detail later.

The means for so mounting the irst actuated member I6 on the rst valve pedestal I3 is best seen in Fig. 3, and comprises a plate 46 positioned horizontally on the two parallel plates 46 of the iirst valve pedestal I3 and secured thereto by welds 41 or other suitable means. Plate 46 is centrally apertured as at 48 to accommodate a cylindrical boss 49 centrally located ion the lower surface 5I of a fulcrum block 50. thereby allowing the fulcrum block to move about avertical axis through the cylindrical boss 49. To loosely secure the fulcrum block-50 on. plate 46, fulcrum block 50 is apertured as at 52 and 53 and cylindrical spacing collars 54 and 55, each having a length greater than the-heightof the fulcrum block 50 and an external diameter less than the diameter of apertures 52 and 53, are loosely positioned therein. A second plate 56 is positioned above the fulcrum block 50, is supported by the spacing collars 54 and 55 and together with plate 41 and two bolts 51 passing through aligned apertures of the cylindrical spacing collars 54 and 55 and nuts 53 loosely secure the fulcrum block 50 on the rst valve pedestal I3. As so secured, fulcrum block 50 has freedom of motion about a vertical axis through the cylindrical boss 49 which motion is limited by the difference in diameters of apertures 52 and 53 and the associated spacing collars 54 and 55 positioned therein.

To provide the iirst actuated member I6 with limited motion about a vertical axis and pivoted motion about a horizontal axis, the rst actuated member I6 is pivotally connected to the fulcrum vblock 58 by means of a bearing shaft 59 passing through aligned apertures 68 and 6I located respectively in the fulcrum block 59 and the parallel arms 43 of the rst actuated member I6.

Actuating member I5 is connected to the first actuated member I6, as best shown in Fig. 2, by means of the rst pair of parallel tension members I8. Considering the action of tension members I8, it will beobvious that if one of the members I8 were heated more than the other by reason of the steam in steam chest I or in a turbine connected thereto, such unequal heating of members. I8 would cause one member I8 to be elongated withrespect to the other member I8 with the consequent result of a twisting effect on first actuated member I6, bearing shaft 59, and the iirst valve pedestal I3. Such twisting would produce detrimental stress, binding and wearing of the members'mentioned, and. it is for this reason that means has been provided, as previously described, allowing limited oscillation of first actuated member I6 about a vertical axis to compensate for. such unequal expansion of the tension members I8.

So far we have described the portion of our valve gear necessary to operateone valve operating rod such as 6. If the turbine has only one valve operating rod, as may be the case, no further structure is necessary. However, if the turbine has ajplurality of valve operating rods, then additional Yactuated members, such as the second actuated member I'I, is provided and mounted on thevrsecond valvepedestal I4, as shown in Figs. l and` 2. y The second actuated member I1 is similarin structure to the rst actuated member I6 and is mountedon second valve pedestal I4 by a fulcrum block in the same manner as described f or the iirst actuated member I6 to provide pivotal motion about a horizontal axis andlimitedv rotationV about a vertical axis. The first' and second actuated members are interconnected by a second pair of parallel tension members I9, as shown in Fig. 2, and a bifurcated end I|52 on the second actuated member I1 is pivotally connected to'valve operating rod 1.

Valve operating rods 6 and 1 are biased in a downward or valve closing direction in a conventional manner by means of respective springs 63and64. v v

To understand the. operationv of the valve gear I0 as above described, attention is now directed to Fig. 1. Toopen inlet valves 3 in steam chest I, piston 24 is moved in an upward direction by oil under pressure admitted through a pipe 65, thus pivoting actuating member I5 in a clockwise direction through the medium of piston rod 36. Actuating member I5, through the rst pair of parallel tension members I8, pivots the first actuated member I6 in a clockwise direction also, thus exerting an upward pull on valve operating rod 6 through thev medium of the bifurcated end 45 of the rst actuated member I6. The second actuated member I1 is also vpivoted in a clockwise direction, by means of the second pair of parallel tension members I9 pivotally interconnecting the first and second actuated members, vthereby exerting an upward pull on valve operating rod 'I through the bifurcated end 62. When valve rods B and 1 are pulled upward, the cross member Eis'raised thereby opening the intake 'valves 3 in succession to supply steam to a turbine 'through the 'inlet passages 9.

To close the valves 3, springs 63 and 64 connected respectively on the valve rods 6 and 'I act in conjunction with spring 25 of the `hydraulic motor 2| to reverse the movement'of the valve gear I0.

It will be apparent from the above description that main frame plate Il forms a rigid cantilever beam reenforced by truss pedestal I2 -to prevent deflection of the projecting end 20 6. second bell-crank actuated -member `having 4a pair ofspacedpara-llel vertically disposed arms and va 'pair of4 horizontally disposed spaced Aparallel arms with endportions secured to v'a bridge frame member having vvan end portion adapted to be pivotally-securedto a valve 4actuating member, universal pivot meansysupporting the actuated memberonsaid second pedestal for pivotal motion about ahorizontal laxis and limited oscillation about a `vertical axis, and "a ,pair of hori- Zonta-ily disposed lparallel ntension links having end portions pivoted .to the vrespective vertical arms. of isaidactuating and :actuated members, wherebyvdifferential thermal expansion of said te'nsionjlinksy produces `slight yoscillation about a vertical axis of said lactuated bell-crank lever member.

j 2.; In a valve vactuating gear for an elastic iiuid turbine or like machine, the combination of a horizontally disposed main frame member adapted to support actuating motor means on one end thereofand having another portion adapted to be secured to the frame of the machine, a i'irst thereof. It will also be apparent that actuating member I5 and actuated members I6 and I1 are relatively short members of rigid structure thereby offering a substantial resistance to bending, and that members I8 and I9, which provide the necessary length to the linkage, are tension members and therefore are not subject to deection and bending.

We have, therefore, provided a valve gear of improved resistance to bending or deflecting of its members thereby making possible the mounting of an oil pressure motor at a safe distance laterally disposed from the valve operating rods of a steam turbine or like machine to prevent re hazard due to oil leaking from the hydraulic motor, while permitting accurate regulation of steam supplied to the machine.

While the motor 2l has been represented as a hydraulic cylinder, it will be obvious that other suitable types of linear or cam actuators might also be used to position the horizontal arm I5.

While we have shown and described a particular embodiment of our invention, it will be obvious to those skilled in the art that various changes and modiiications may be made without departing from our invention in its broader aspects and we, therefore, aim in the appended claims to cover all such changes and modications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. In a valve gear for an elastic fluid turbine or like machine, the combination of an elongated horizontally disposed main frame member adapted to support a hydraulic motor on one end thereof and having another portion adapted to be secured to the frame of the machine, a truss pedestal projecting upward from the frame member adjacent the motor end thereof, a rst bell-crank actuating lever member having a rst pair of vertically disposed spaced parallel arms and a second pair of horizontally disposed spaced parallel arms connected to a bridge frame member with an end portion adapted to be connected to the hydraulic motor, pivot means connecting the mid-portion of said actuating lever member to the truss pedestal for pivotal movement about a horizontal axis transverse to the main frame, a second pedestal member disposed vertically above the main frame and secured thereto in spaced relation to the truss pedestal, a

pedestal member projecting upward from the frame member adjacent the motor end thereof, a iirst bell-crank lever member having a pair of spaced parallel vertical arms and a horizontally disposed arm member within an end portion adapted to be connected to the motor, pivot means supporting the mid-portion of said rst lever on the iirst pedestal for pivotal movement about a horizontal transverse axis, a second pedestal member disposed vertically above the frame member and secured thereto in spaced relation to the first pedestal, a second bell-crank lever member having a pair of spaced parallel vertical arms disposed on either side of the second pedestal and a horizontally disposed arm with an end portion adapted to be connected to a valve actuating member, universal pivot means supporting said second lever member on the second pedestal for pivotal movement about a horizontal axis and limited oscillation about a vertical axis, and a pair oi" horizontally disposed parallel tension links with end portion pivoted to the respective ends of the vertical arms of the rst and second bell-cranks whereby any diiierential thermal expansion occurring between said tension links will produce slight oscillatory adjustment of the second bell-crank about a vertical axis.

3. In a valve actuating gear for an elastic fluid turbine or like machine, the combination of an elongated horizontally disposed frame member adapted to support actuator means` on one end thereof and having another portion adapted to be secured to the frame of the machine, a iirst pedestal member projecting upward from the frame adjacent the actuator end thereof, a iirst bell-crank actuating lever member having a pair of vertical spaced parallel arms and a horizontally disposed arm member with an end portion adapted to be connected to the actuator, pivot means connecting the mid-portion of said actuating lever member to the iirst pedestal for pivotal movement about a horizontal axis transverse to the frame, a second pedestal member disposed vertically above the frame and secured thereto in spaced relation to the iirst pedestal, a second bell-crank lever member having a pair of spaced parallel vertical arms disposed on either side of the second pedestal and a horizontally disposed arm member with an end portion adapted to be connected to a iirst valve actuating member, iirst universal pivot means supporting said second lever member on said second pedestal for pivotal motion about a horizontal transverse axis and limited oscillation about a vertical axis, a third pedestal member disposed vertically above the frame and secured thereto in spaced relation to the second pedestal at the side thereof remote from said rst pedestal, a third bell-crank lever member with a pair of vertical spaced parallel arms disposed at either side -of said third pedestal and a horizontally disposed armwith an end portion adapted to be connected to a second valve actuating member, second universal pivot means supporting said third bell-crank member on said third pedestal for pivotal motion about a. horizontal transverse axis and vlimited oscillation about a vertical axis, arst pair of horizontally disposed parallel links having end portions pivoted to the respective vertical arms of said first and second bell-crank levers, and a second pair REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 528,483 Nixon Oct. 30, 1894 628,101 Lewis July 4, 1899 936,261 Warren Oct. 5, 1909 

